Placer-mining dredge



(N0 Model.) 3 Swam Sheet I.

- A. W. ROBINSON.

PLACER MINING DREDGE.

N Patented Sept. 14,1897.

(No Mbdel.) A 3 Sheets-Sheet 2.

A. W. ROBINSON.- PLACER MINING DREDGE.

No. 589,868. Patented Sept. 14,1897.

n1: nouns vgrcns co. PHOTQUTHO. WASHINGYON, u. c.

UNITED STATES PATENT Grinch,

ARTHUR W. ROBINSON,- OF MILWAUKEE, \VISGONSIN.

PLACER-MINING DREDGE.

PECIFICATION forming part of Letters Patent No. 589,858, dated September14, 1897.

Application filed April 22, 1897.

To U whom it may concern.-

Be it known that I, ARTHUR W. Rosruson, a citizen of Canada, and aresident of Milwaukee, in the county of Milwaukee and State ofWisconsin, have invented certain new and useful Improvements inPlacer-Mining Dredges, of which the following is a specification.

My invention relates to improvements in placer-mining dredges; and itconsists in the construction and arrangement of the parts as hereinafterset forth.

The essential characteristics or features 0 the invention are a scow orequivalent support upon which are erected excavating apparatus,preferably endless-chain buckets, which discharge into a grizzly orequivalent screen,in which the coarser material and other impurities areseparated, being discharged overboard from the tail of the grizzly, andthe finer material, carrying the gold or other valuable metal, passesthrough the grizzly and is received in a box or hopper having a chutewhich discharges into another hopper submerged below the surface of thewater, and a suction-pipe connects with this last-named hopper with theeye of a centrifugal pump, so that the material received from thegrizzly in conjunction with the water which flows in at the mouth of thehopper is sucked from the latter into the centrifugal pump and by itdischarged into a sluice-box, which is likewise carried by the dredge orequivalent sup port, the interior of which is provided with the usualamalgam steps or equivalent devices for separating and retaining themetal, and from the tail of the sluice-box a conduit is provided wherebythe waste or detritus is carried to a suitable dumping-place.

Referring to the drawings, Figure 1 illustrates a plan of adredgeembodying the invention, certain of the parts being omitted for the sakeof clearness. Fig. 2 illustrates an elevation of that which is shown inFig. 1, excepting that the grizzly and some of the other parts areomitted for the sake of clearness. Fig. 3 illustrates a side elevationof the submerged. hopper, the body of the scow being sectioned at theleft to show its con struction. Fig. at illustrates a view, partly insection and partly in elevation, taken from the front of the scow.

gerial No. 633,220, No model) ing-buckets E, carried by a boom F, may beemployed. These parts may be differently arranged and constructed, ifdesired. The upper axis of the chain of buckets is shown at G, it beingdriven by a suitable sprocketwheel H in conjunction with proper drivingmechanism. As the buckets E revolve they discharge into a hopper, thelower portion of' which is shown at I in Fig; at, which connectswith anordinary rotating grizzly J, the tail of which, K, discharges overboard.This grizzlyis supported and actuated in any-usual or preferred manner.On the under side of the grizzly (see Fig. 4) is a hopper or receptacleL, which catches the finer material and the gold or other precious metalwhich pass through the grizzly. From this receptacle L there is a chuteM, which delivers it into a hopper N, which is submerged below thesurface of the water 0. This hopper N is supported upon a pipe P, whichconnects with the eye Q, of a centrifugal pump R, and the connection atR is a pivotal one, so that if anything should clog the pipe P it andthe hopper carried by it can be swung upwardly, as shown in dotted linesin Fig. 3, and the obstruction removed. There are cars or rings Sattached at the sides of the hopper whereby a chain can be made fast toit for the purpose of lifting it. The centrifugal pump R dischargesthrough apipe T, which empties into the upper end of a sluice-box U,which is supported by the dredge in an inclined position, as shown, andwithin which are the usual amalgam steps or boxes or other equivalentmechanism for separating and retaining the precious metal in a mannernow well understood, and from the tail of the sluice-box U the exhaustedmaterial or detritus passes into a conduit V, whereby it is conveyed toa suitable dump.

It will be understood that the several parts above referred to areprovided with suitable coacting parts and with actuating or drivingmechanism, some portions of which are illustrated upon the drawings; butrelative to those matters no description or explanation is necessary,since their construction and op eration may be such as preferred, therebeing a large number of appliances suitable for the purpose now incommon use and well known to those familiar with this art.

The operation is as follows: The excavating instrumentalities, whateverthey may be, lift the submerged gold bearing material from the bottom ofthe placer and deposit it in the hopper, from which it passes into thegrizzly, by which the coarser material, such as rocks, lumps, &c., areseparated from the finer gold-bearing material and discharged overboardfrom the tail of the grizzly. The finer gold-bearing material, however,passes through the grizzly and is received in thebox or hopper L beneathit, from which it passes through the chute M int-0 the submerged hop.per N, within which there isa strong suction generated by thecentrifugal pump, so that the finer material, together with the preciousmetal or metals, are drawn into the hopper and through the pipe P intothe eye of the centrifugal pump R, from which they are in turn ejectedthrough the pipe T and into the sluice-box U, in which the preciousmetal is separated by the Well-known employment of quicksilver oramalgam, so called, and is thus held within the sluice-box while thedetritus passes off from the tail of the sluice-box through thedischarge chute or conduit V.

It will be obvious to those who are familiar with this art thatmodificationsmay be made in the construction and arrangement of theparts without departing from the essentials of the invention. Itherefore do not limit myself to the details described and shown.

I claim 1. The combination with a scow orlike support of excavatingmechanism, a rotary and positively-driven screen, a submerged hopper, acentrifugal pump and means to feed the material from one to the othersuccessively, for the purposes set forth.

submerged hopper, pivotally supported, so

that it may be elevated above the Water, a centrifugal pump, and meansto feed thematerial from one to the other, for the purposes set forth.

4. The combination with a scow or like device, of excavating mechanism,a screen, a submerged hopper connected with a pipe piv ot-ally connectedto the eye of a centrifugal pump, said centrifugal pump itself and meansto feed the material from one to the other of said instrumentalities,successively, for the purposes set forth.

5. The combination with a scow or like support of a submerged hoppersupported upon a pipe which is pivotally connected to the eye of acentrifugal pump and an amalgam-tank or. sluice box into which said pumpdischarges, for the purposes set forth.

6. The combination of a scow upon which the following instrumentalitiesare supported, to wit, excavating apparatus which discharges into agrizzly or screen, a receptacle beneath the grizzly which catches thefine material, and which discharges into a submerged hopper, saidsubmerged hopper itself, a pipe or conduit connecting it with asuction-pump, and a discharge conduit or pipe which connects the pumpwith an amalgamtank or sluice-box, for the purposes set forth.

Signed at Milwaukee, in the county of Milwaukee and State of lVisconsin,this 16th day of April, A. D. 1897.

ARTHUR W. ROBINSON.

YVitnesses:

J. M. MILLMAN, J. G. DAVIES.

